﻿//-----------------------------------------------------------------------
// <copyright file="Download.ashx.cs" company="OOHM PROCESSAMENTO DE DADOS LTDA.">
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//-----------------------------------------------------------------------
namespace AbstractSaaSTemplate.UI.Web.Content.Blobs{    using System;
    using System.Globalization;
    using System.Web;
    using AbstractSaaSTemplate.Application.Localization;
    using AbstractSaaSTemplate.Domain.Repositories;

    /// <summary>
    /// The download handler that will be used to download
    /// blobs from the system from inside out the application.
    /// </summary>
    public class DownloadHandler : IHttpHandler
    {
        /// <summary>
        /// Initializes a new instance of the DownloadHandler class.
        /// </summary>
        public DownloadHandler()
        {
            this.RepositoryForFiles = this.GetRepositoryFor<IBlobRepository>();
        }

        /// <summary>
        /// Initializes a new instance of the DownloadHandler class.
        /// </summary>
        /// <param name="repositoryForFiles">The repository to operate 'Files'.</param>
        public DownloadHandler(IBlobRepository repositoryForFiles)
        {
            this.RepositoryForFiles = repositoryForFiles;
        }

        /// <summary>
        /// Gets the repository to opreate 'Files'.
        /// </summary>
        public IBlobRepository RepositoryForFiles { get; private set; }

        /// <summary>
        /// Gets a value indicating whether another request can use the System.Web.IHttpHandler
        /// instance.
        /// </summary>
        public bool IsReusable
        {
            get
            {
                return false;
            }
        }

        /// <summary>
        /// Enables processing of HTTP Web requests by a custom HttpHandler that implements
        /// the System.Web.IHttpHandler interface.
        /// </summary>
        /// <param name="context">An System.Web.HttpContext object that provides references to the intrinsic server objects (for example, Request, Response, Session, and Server) used to service HTTP requests.</param>
        public void ProcessRequest(HttpContext context)
        {
            if (context == null)
            {
                throw new ArgumentNullException("context");
            }

            var id = context.Request.QueryString["id"];
            if (string.IsNullOrWhiteSpace(id))
            {
                context.Response.TrySkipIisCustomErrors = true;
                context.Response.Clear();
                context.Response.StatusCode = 500;
                context.Response.StatusDescription = Messages.NotPossibleToRetrieveBlobWithoutItsId;
                if (!MvcApplication.LaunchedFromUnitTest)
                {
                    context.Response.Write(context.Response.StatusDescription);
                }

                context.Response.End();
                return;
            }

            var fileId = Guid.Empty;
            if (!Guid.TryParse(id, out fileId))
            {
                context.Response.TrySkipIisCustomErrors = true;
                context.Response.Clear();
                context.Response.StatusCode = 404;
                context.Response.StatusDescription = string.Format(
                    CultureInfo.CurrentUICulture,
                    Messages.BlobXNotFound,
                    fileId.ToString());
                if (!MvcApplication.LaunchedFromUnitTest)
                {
                    context.Response.Write(context.Response.StatusDescription);
                }

                context.Response.End();
                return;
            }

            var file = this.RepositoryForFiles.GetBlobById(fileId);
            if (file == null)
            {
                context.Response.TrySkipIisCustomErrors = true;
                context.Response.Clear();
                context.Response.StatusCode = 404;
                context.Response.StatusDescription = string.Format(
                    CultureInfo.CurrentUICulture,
                    Messages.BlobXNotFound,
                    fileId.ToString());
                if (!MvcApplication.LaunchedFromUnitTest)
                {
                    context.Response.Write(context.Response.StatusDescription);
                }

                context.Response.End();
                return;
            }

            var buffer = new byte[file.Stream.Length];
            file.Stream.Read(buffer, 0, buffer.Length);
            file.Stream.Position = 0;
            
            context.Response.ContentType = file.ContentType;

            // fails on unit test due to problems with the OutStream mocking
            if (!MvcApplication.LaunchedFromUnitTest)
            {
                context.Response.OutputStream.Write(buffer, 0, buffer.Length);
            }
            
            context.Response.AddHeader("filename", file.OriginalName);
            context.Response.AddHeader("fileSize", buffer.Length.ToString(CultureInfo.InvariantCulture));
        }
    }
}

